Sharpening stones, or hones, are typically provided as relatively thick elongated slabs having a large, flat upper surface on which blades can be sharpened. The use of the term "sharpening stone" can pertain to conventional solid abrasive stones or, in a more modern sense, to any strong solid material having an abrasive surface layer. In recent years industrial grade diamonds have proliferated on the world market, in the process becoming less expensive, and are often preferred for forming an abrasive coating or layer on grinding wheels and other sharpening devices. Accordingly, relatively brittle solid sharpening stones of the past may be replaced by rectangular bars of steel covered with a coating of abrasive industrial grade diamonds.
When sharpening a knife or other instrument, the angle at which the blade is held with respect to the sharpening surface is critical. The angle must be held relatively constant while the blade is rubbed over the sharpening surface otherwise ineffective or uneven sharpening will occur. There have been numerous designs in the past to provide holders or stands for sharpening stones to ensure a correct angle is ground into the blade. For example, U.S. Pat. No. 4,991,357 to Stickles, Sr. discloses a knife-sharpening kit wherein a sharpening stone is mounted between a pair of angled support surfaces on which the blade rests during sharpening. The kit is provided with a separate hollow cover to protect the sharpening stone when not in use.
Although devices for holding the blade at a certain angle have been in use for many years, the most popular sharpening stones remain the simple flat surface so that the person sharpening the blade can adjust the angle and with care produce a fine sharp edge. There have been attempts at providing a container for such flat stones which can render them portable and which are openable to expose the stone to sharpening. Such containers may be seen in U.S. Pat. No. 337,559 to Cole, U.S. Pat. No. 816,559 to Pippy, and U.S. Pat. No. 2,324,498 to Emmert. The Cole and Pippy oil stone holders are relatively bulky and intended for use with a lubricating oil with oil receptacles provided. Specifically, the lower portion of the Cole holder contains oil, while the lid of the Pippy box when inverted underneath the stone catches excess oil from around the sides of the holder. The device of Emmert is a relatively flimsy embossed paper sheet having the hone attached to inner surfaces. Another attempt at providing a portable protective container for an abrasive stone is shown in U.S. Pat. No. 329,425 to Homeyer. An endless band of rubber surrounds the stone and may be peeled back and folded underneath to provide a non-slip base when sharpening.
Despite the aforementioned attempts, there is still a need for a portable, lightweight, and relatively simple device for containing sharpening stones and exposing them for use in sharpening blades.